Rotary piston machines

ABSTRACT

A central axis rotary piston machine, e.g., a motor or a pump. A pair of diametrically opposed sector-shaped hollow blades are mounted on rotation on each of two coaxial shafts and arranged in a housing including a pair of flanges fixed to the blades and a fixed enclosure extending about the blades. Each flange is also provided with an opening in communication with the hollow interior of the blade on which it is fixed. The relative angular position of the blades on one shaft with respect to the blades on the other shaft is determined by meshing quasi-elliptical gear wheel in cooperation with a differential gear which is provided for reducing the forces of inertia for given angular velocities. The differential gear includes a differential wheel mounted for rotation with each of the shafts, star pinions, and gear wheels for mounting the star pinions which transmit power between the machine and means external to the machine and having relatively slow speed variations. The degree of compression in the chambers of variable volume formed between consecutive blades is determined by the formula : t Beta - delta / Alpha - delta where delta is the angle included between the radial side of the sector-shaped blades, and Alpha and Beta are the angles defining the limit positions of the center line of consecutive blades on alternate shafts movable towards and away from each other during the operating cycle of the machine.

nited States Patent Bees [ 1 Mar. 25, 1975 1 ROTARY PISTON MACHINES [76] Inventor: Jean Bees, 61 Avenue de la Bourdonnais, Paris 7eme France [22] Filed: Oct. 15, 1973 [21] Appl. No.2 406,307

[30] Foreign Application Priority Data Oct. 19, 1972 France 72.37065 [52] 11.5. C1. 418/36 [51] Int. C1. F010 21/00 [58] Field of Search 418/36 [56] References Cited UNITED STATES PATENTS 1,962,408 6/1934 Powell 418/36 2,342,515 2/1944 Morgenstern 418/36 3,294,071 12/1966 Turco 418/36 3,302,625 2/1967 Cunningham 418/36 3,356,079 12/1967 Rolfsmeyer 418/36 3,398,643 8/1968 Schudt 418/36 3,769,946 11/1973 Scherrer 418/36 [57] ABSTRACT A central axis rotary piston machine, e.g., a motor or including a pair .of flanges fixed to the blades and a fixed enclosure extending about the blades. Each flange is also provided with an opening in communica' tion with the hollow interior of the blade on which it is fixed. The relative angular position of the blades on one shaft with respect to the blades on the other shaft is determined'by meshing quasi-elliptical gear wheel in cooperation with a differential gear which is provided for reducing the forces of inertia for given angular velocities. The differential gear includes a differential wheel mounted for rotation with each of the shafts, star pinions,- and gear wheels for mounting the star pinions which transmit power between the machine and means external to the machine and having relatively slow speed variations. The degree of compression in the chambers of variable volume formed between consecutive blades is determined by the formula t= [3-8101 8 where 6 is the angle included between the radial side of the sector-shaped blades, and a and Bare the angles defining the limit positions of the center line of consecutive blades on alternate shafts movable towards and away from each other during the operating cycle of the machine.

PATENTEBHARZSIQYS 3.873 .247

SHEET 1. or 4 PATENTEDHARZSIHYS I 3,873,247

SHEET 2 9 2 Fig 3 PATENTEU 2 5 I975 SHEETBUFZI t ROTARY PISTON MACHINES The present invention relates to rotary piston machines.

Numerous studies and considerable amounts of research concerning such machines have been carried out. A nomenclature of various proposed systems has been produced by Felix Wankel, entitled: Rotary Piston Machines.

Central axis rotary piston machines essentially comprise two concentric shafts mounted for rotation about the same axis, each shaft carrying a series of blades and rotated in the same direction at variable relative speeds which varies the angle between a blade carried on one shaft and a blade carried on the other shaft.

The blades are movable inside the same housing of revolution about the common axis of rotation and define chambers whose volumes vary as a function of the angle between the blades on the respective shafts. These variations in volume of the chambers are used to effect the induction or admission, compression, power and exhaust phases of the operating cycle which is common, namely, in internal combustion engines.

The thickness and shape of the blades vary according the proposed arrangement. A suitable choice of the variables enables the opening and closing of the admission (intake) port and the exhaust port formed in the wall of the housing at appropriate moments.

Although such engines date back to before 1919, we have seen in the past 20 years a profusion of patent literature and projects relative to the same, however, these efforts have apparently not been followed up. The major criticism of such engines is that the variation of forces of inertia due to the variations in angular velocity subject the movable elements to very high reaction forces. It must be noted, however, that these phenomena are found to at least the same degree in conventional internal combustion engines where such a drawback has not prevented the obtaining of results which are considered acceptable.

Certain authors classify central axis rotary piston machines into two categories according to the way in which the variations in angular velocity are obtained.

In a first category of machines, the sought-after result is obtained by alternately locking and unlocking each of the shafts against rotation: the angular velocity of one of the shafts varies as follows:

V V 0 while the angular velocity of the other shaft varies during the same period as follows:

Numerous devices have been proposed for locking the shaft against rotation including pawls and ratchets, direct drive dog clutch, other clutch mechanisms, free wheel with locking mechanism, crank arms, slide cranks and torsion cranks, wheels with toothed and smoothed portions, positive mountings. On the whole, these devices are delicate and only permit relatively low power transmission and angular velocities, or they have parts which are subject to reciprocating movements which considerably aggravates the problem of variations in the force of inertial mentioned above.

In the other category ofmachines, the angular velocities of the shafts vary within relatively narrow ranges and never pass through a zero value, the velocities of a first shaft of such machines can be schematically described as follows:

1 2 1 2 while the angular velocities of the second shaft of such a machine during the same time period can be schematically described as follows:

This result is obtained by the use of noncircular rolling curves, namely in the form of so-called quasielliptical gearing.

For the purpose of this specification the term quasielliptical gearing means gearing comprising two identical cooperating toothed wheels of generally elliptical shape, e.g., slightly modified along the major curved sides thereof. It is known that two identical ellipses each turning about the intersection of its major and minor axes or center forms rolling curves, i.e., they can turn on one another without sliding, the point of contact remaining fixed along the line joining the two centres of rotation. It is also known that the same ellipses, each turning about its center, are not rolling curves, however, the correctionrequired so that they are rolling curves is relatively small, if their elongation is moderate.

The calculation of the exact curve or quasi-ellipse which is known in mathematics as a double-lobed rolling curve is well known and will not be reproduced here.

A description of an embodiment of the invention follows, made by way of example, with reference to the accompanying drawings, in which:

FIGS. 1 and 2 show theoretical diagrams of pseudoelliptical gearing;

FIG. 3 shows a cross-sectional view of a motor according to a preferred embodiment of the invention;

FIG. 4- shows an end view of the motor illustrated infigure 3;

FIG. 5 is a simplified end view on a small scale of a gear train comprising quasi-elliptical gear wheels;

FIG. 6 shows a position diagram indicating the various phases of operation of the motor;

FIG. 7 shows a diagram illustrating the position of the sparking device, the admission means and the exhaust means for the same motor.

A few important properties of quasi-elliptical gearing will now be brought out with reference to FIGS. 1 and 2. a

If a and b are respectively the lengths of half the major axis and half the minor axis of the quasi-ellipses, and r, and r are the distances from the point of contact M of the quasi-ellipses to the centers 0 0 with r, r a b, when r r the two wheels rotate at the same angular velocity. It is easy to see that there are four points so-called constant velocity or homokinetic points on each quasLellipse: A B C D and A B C D defined by A O =(a b)/2=O,B,, etc.

If we call a and B the angles between the radii corresponding to the constant velocity points, we see that one gear wheel turns through an angle a while the other turns through an angle B. If the movement of the quasiellipses is applied to the blades of a machine with concentric shafts, the difference a ,8 corresponds to the variation in angle between the blades defined by their center lines.

Although the above principles are applicable to various types of machines, in particular, pumps or injection engines, a preferred non limiting example of the invention will now be described relative to an application in internal combustion engines.

The construction of the blades is preferably as follows:

A pair of blades are arranged diametrically each other on each shaft. The blades are sector-shaped, the angle between their radial sides being defined so that the ratio of the maximum and minimum volumes of the chambers defined by two consecutive blades a first blade on one shaft and a consecutive blade on the other shaft is equal to the desired degree of compression. In other words, it could be said that between the angle 8 included between the sides of the blade and the angles a and B define the extreme relative positions of the center lines of the blades and the degree of compresslon t:

The maximum difference between the angular velocities of the quasi-ellipses is reached when an end of the major axis is in contact with an end of the minor axis of the other quasi-ellipse (FIG. 1), the ratio of the angular velocities is therefore: 11/); or b/a.

If one of the quasi-ellipses rotates at a constant angular velocity V, the angular velocity of the other quasiellipse varies between V X a/b and V X b/a.

For example, if a/b 2, the angular velocity varies between 2V and 5V.

This is normally the case if one of the quasi-elliptical gear wheels is fixed to a shaft rotating at a practically constant angular velocityzdriven shaft in the case of a motor or driving shaft in the case of a pump.

It follows that if the ratio of the major to minor axes of the ellipses is n, the ratio of the greatest to smallest rotational velocity of the shaft of variable angular velocity will be n therefore the ratio of maximum to minimum forces of inertia will vary as the square of the angular velocity ratio, Le, 11*, which considerably limits the applications of such gearing in high angular velocity ranges.

An aim of the invention is to overcome this problem.

An aspect of the invention consists in coupling with a pair of quasi-elliptical gear wheels a conventional type of differential gear, each one of the shafts being fixed to one of the bevel or differential wheels.

If the gear wheel carrying star or differential pinion is controlled to turn at a constant angular velocity V, this angular velocity V is the arithmetic mean of the angular velocities V and V of the bevel or differential wheels.

Therefore, V V 2 V from which we find that V, varies between n l )V/2 and (n l) V/2n while V varies between (n l)V/2n and (n 1) W2, that is, with a ratio of maximum to minimum angular velocities of n and not H as in the case in which a differential gear is not used, and a ratio of n for the forces of inertia instead of n*.

The considerable resultant improvement in the re duction of inertial forces is immediately seen.

FIG. 3, described below, shows a gear train embodiment in which a quasi-elliptical gear wheel is fixed to one of the coaxial shafts and a circular gear wheel is fixed to the other coaxial shaft. A second quasielliptical gear wheel and a second circular gear wheel identical to the first circular gear wheel are keyed to an auxiliary shaft. The differential gear is arranged in a continuation of the coaxial shafts.

It is obvious that other equivalent arrangements are possible within the scope of the invention. For example, the gear train may have two or more quasielliptical gear wheels instead of one quasi-elliptical gear wheel and one circular gear wheel provided that the angular variations and the variations in the angular velocity-of the blades remain the same. In this case less elongated quasi-elliptical gear wheels are used which results in reduced machining costs.

Further, the differential gear may be positioned outside the axis of the blades for space considerations.

According to a preferred operating conditions of the invention, this reduction of the forces of inertia is used in part to improve the heat flow patterns in the blades.

Indeed, in such a machine as described above having rotary blades arranged in a closed housing, the over heating of the blades poses difficult problems which would hardly be resolved economically.

The housing is divided into three sections: two lateral rotary flanges and a fixed enclosure. A flange is fixed to each of two diametrically opposed blades fixed to the same shaft.

This arrangement which adds the inertia of the flange to the inertia of the blade is only economically possible by the use of the above-described differential gear.

If the blades are of generally square or rectangular shape, the flanges are formed as flat discs and the enclosure is formed as a cylinder, however, this arrangement is not obligatory.

The-blades thus transfer heat to the flanges, the external face of the flanges may be cooled by suitable known cooling means. It is also possible to provide a hollow blade communicating with the exterior through one or more apertures passing through the flange. A

coolant may thus introduced inside the blade itself. A

particularly simple and economic construction brings the interior of the blade directly into contact with the ambient air. An air cooling is thus provided which is more efficient and advantageous than usual devices. This arrangement could also be combined with another cooling fluid inlet by the shaft carrying the blade.

Preferably, advantage of the particular construction of the housing is taken to provide slide valves in front of the admission and exhaust ports. It is thus possible to adapt simply, even during operation, the dimensions of the ports to the operating characteristics, e.g., rotational velocity, nature of fuel, temperature. In this case, the pollution caused by the exhaust fumes of the engine may be very substantially reduced by using the socalled Stratification technique.

FIGS. 3 and 4 illustrate a practical embodiment of the motor according to the invention.

An inner shaft 1 extends through the entire apparatus and is supported by bearings 31 and 32 at its respective ends. An outer shaft 2 is supported by a bearing 33 and is coaxial with the inner shaft 1. Blades 3 and 4 are fixed to the flanges 7 mounted for rotation with the inner shaft 1, and blades 5 and 6 are fixed to another flange 8 mounted for rotation with the outer shaft 2.

The blades 3-6 are annular sector-shaped with 53 angle 8 between the radial side thereof. The blades are hollow and do not have a wall on the side facing the flange on which they are fixed. The flanges have a corresponding opening 9,9' of substantially the same dimension as the interior of the blade thereby giving ample access to the ambient air ensuring the cooling of the blades.

The cylindrical enclosure closes the housing and is provided with a peripheral groove 11 for facilitating its cooling. The sparking plug and the admission and exhaust ports (not shown in the drawings) are arranged in the enclosure.

A quasi-elliptical gear 12 is keyed to the outer shaft 2 and drives a similar quasi-elliptical gear 13 keyed to an auxiliary shaft 14 (FIG. 5). A circular gear wheel 15 is keyed to the inner shaft 1 and'drives an identical gear wheel 16 keyed to the auxiliary shaft 14.

A differential or bevel wheel 17 is fixed to the outer shaft 2 for movement with the quasi-elliptical gear wheel 12, the other differential or bevel wheel 18 is fixed to the inner shaft 1 for movement with the circular gear wheel 15.

The gear wheel 19 carrying the star pinion 19 freely swivels on the inner shaft 1 and drives the output shaft.

21 through the intermediary of a gear wheel 20.

The quasi-elliptical gear wheels 12 and 13 are sized so as to give a maximum angular separation 01 of l and a minimum angular separation B of 60 between the centre lines of consecutive blades on alternate shaft which approximately correspond to a value of 2 for the ratio a/b of the lengths of the axes of the ellipses.

and the minimum and maximum volumes of the chambers correspond respectively to apex angles of 7 and- The positions of the walls A-H of the blades and the values of the central angles AOB, COB, EOF, GOH of chambers I, II, III, IV are indicated in the accompanying table, the position M 0 described in the first line of the table, corresponding to the position in FIG. 6,

' i.e., at the moment the blades are at their maximum or minimum separation.

The abbreviations POWER, EXH, ADM and COMP correspond to the power, exhaust, admission and compression phases of the operating cycle.

The sparking plugs B are arranged at 2630, the admission ports A are arranged between l5330 and 20630 and the exhaust ports E are arranged between.

TABLE angular position of the at least one blade of one shaft with respect to the at least one blade of the other shaft, a gear train including an auxiliary shaft, two quasielliptical gear wheels in engagement with each other and carried by said auxiliary shaft and one of said coaxial shafts, other gear wheels in engagement with each other and carried by said auxiliary shaft and the other of said coaxial shafts, and a differential gear including two differential wheels each mounted to be driven by one of said coaxial shafts, a start pinion in meshing engagement with the differential wheels and a gear wheel carrying the star pinion for transmitting power between the machine and means external to the machine and having relatively slow speed variations.

2. A machine according to claim 1, wherein the housing comprises a fixed enclosure and flanges mounted for rotation with the blades, the flanges having means for transferring heat from the blades to the surroundings during operation of the machine.

3. A machine according to claim 2, wherein each blade is hollow, and said means for transferring heat includes its respective flange being provided with aperture means for enabling the circulation of a coolant between the hollowed interior of said one blade and the surroundings of the housing.

4. A machine according to claim 1, wherein each series of blades comprises a pair of diametrically opposed sector-shaped blades, an angle 8 included between the radial sides of the sector-shapped blade being defined as a function of the angles or and B which define the extreme limit positions of the centre line of the blades and the degree of compression according to the formula:

5. A machine according to claim 3 wherein said aperture means opens to the surroundings of the housing.

6. A machine according to claim 1 wherein said differential gear is mounted between said quasi-elliptical gear wheel carried by said one coaxial shaft and that one of said other gear wheels carried by said other coaxial shaft.

7. A machine according to claim 1 wherein said differential gear is mounted between said quasi-elliptical gear wheel carried by said one coaxial shaft and that one of said other gear wheels carried by said other coaxial shaft, and in surrounding relation with respect to said other coaxial shaft adjacent an end of said one coaxial shaft.

8. A machine according to claim 1 wherein said quasi-elliptical gear wheels are identical, and each quasi-elliptical gear wheel is modified along major POSITIONS OF VARIOUS POINTS STARTING FROM M 0 III IV AOB COD EOF GOH A B C D E F G H 2630 7 3330 8630 67 l5330 20630 7 2 l 330 26630 67 33330 POW ER EXH ADM COMP 8630 67 l5330 20630 7 2 1 330 26630 67 33330 2630 7 3330 EXH ADM COMP POWER 20630 7 2 l330 26630 67 33330 2630 7 3330 8630 67 l5330 ADM COMP POWER EXH 26630 67 33330 2630 7 3330 8630 67 l5330 206 30 7 2 l 330 COMP POWER EXH ADM 2630 7 3330 8630 67 l5330 7 2 1 330 2663O 67 tances from the centers 0 0 to a point of contact between said quasi-elliptical gear wheels are r r r r =a+b, and when r r said quasi-elliptical gear wheels rotate at the same angular velocity. 

1. A central axis rotary piston machine comprising a housing, two coaxial shafts mounted for rotation in said housing, at least one blade mounted for movement with each of said shafts, means for controlling the relative angular position of the at least one blade of one shaft with respect to the at least one blade of the other shaft, a gear train including an aUxiliary shaft, two quasi-elliptical gear wheels in engagement with each other and carried by said auxiliary shaft and one of said coaxial shafts, other gear wheels in engagement with each other and carried by said auxiliary shaft and the other of said coaxial shafts, and a differential gear including two differential wheels each mounted to be driven by one of said coaxial shafts, a start pinion in meshing engagement with the differential wheels and a gear wheel carrying the star pinion for transmitting power between the machine and means external to the machine and having relatively slow speed variations.
 2. A machine according to claim 1, wherein the housing comprises a fixed enclosure and flanges mounted for rotation with the blades, the flanges having means for transferring heat from the blades to the surroundings during operation of the machine.
 3. A machine according to claim 2, wherein each blade is hollow, and said means for transferring heat includes its respective flange being provided with aperture means for enabling the circulation of a coolant between the hollowed interior of said one blade and the surroundings of the housing.
 4. A machine according to claim 1, wherein each series of blades comprises a pair of diametrically opposed sector-shaped blades, an angle delta included between the radial sides of the sector-shapped blade being defined as a function of the angles Alpha and Beta which define the extreme limit positions of the centre line of the blades and the degree of compression according to the formula: : t Beta - delta / Alpha - delta
 5. A machine according to claim 3 wherein said aperture means opens to the surroundings of the housing.
 6. A machine according to claim 1 wherein said differential gear is mounted between said quasi-elliptical gear wheel carried by said one coaxial shaft and that one of said other gear wheels carried by said other coaxial shaft.
 7. A machine according to claim 1 wherein said differential gear is mounted between said quasi-elliptical gear wheel carried by said one coaxial shaft and that one of said other gear wheels carried by said other coaxial shaft, and in surrounding relation with respect to said other coaxial shaft adjacent an end of said one coaxial shaft.
 8. A machine according to claim 1 wherein said quasi-elliptical gear wheels are identical, and each quasi-elliptical gear wheel is modified along major curved sides thereof from a true elliptical shape to define a double-lobed rolling curve.
 9. A machine according to claim 11 wherein each quasi-elliptical gear wheel has a one-half major axis of a length a and a one half minor axis of a length b, said quasi-elliptical gear wheels have centers 01, 02, the distances from the centers 01, 02 to a point of contact between said quasi-elliptical gear wheels are r1, r2, r1+ r2 a+b, and when r1 r2 said quasi-elliptical gear wheels rotate at the same angular velocity. 